The present invention concerns new 3-amino-5-hydroxypyridine derivatives, as well as compositions for the oxidative coloration of hair, based upon developer and coupler substances, wherein the new 3-amino-5-hyroxypyridine derivatives are employed as coupler substance.
Oxidation dyes have developed an essential significance for hair coloration. The coloration is produced with this class of dyes by means of reaction with determined developer substances with determined coupler substances, in the presence of a suitable oxidation agent.
As developer substances, preferably 2,5-diaminotoluene, 4-aminophenol and 1,4-diaminobenzene have been employed, however also 2,5-diaminoanisol, 2,5-diaminobenzylalcohol and 2-(.beta.-hydroxyethyl)-1,4-diaminobenzene have acquired a certain significance. In certain cases, also tetraaminopyridine can be employed as developer substance. The preferably employed coupler substances are m-phenylendiamine and its derivatives, 2,4-diaminoanisol and 2,4-diaminophenetol, resorcin, 4-chlorresorcin, 1-naphthol, m-aminophenol and 5-amino-o-cresol. The last-mentioned compounds, on account of their ability to provide red tones after oxidative coupling with 1,4-diaminobenzene or 1,4-diaminobenzene derivatives, acquired significance as coupler for the nuancing of natural and so-called mod tones.
Numerous particular requirements are placed on oxidation dyes that are supposed to be employed for the coloring of human hair. Thus, they must be harmless both from a toxicological and dermatological point of view, and make possible the obtaining of colorings of the desired intensity. Moreover, it is necessary that a broad palette of different color nuances can be obtained through a combination of suitable developer and coupler components. Additional requirements for the obtainable hair colorations are a good fastness to light, permanent waving, acid and rubbing. In each case, however, such hair colorations must remain stable, i.e., without influence of light, chemical means or rubbing over a time period of at least 4-6 weeks.
M-aminophenol, employed for some time in hair dyes as a red coupler, its derivatives as well as 5-amino-o-cresol, as well as the likewise employed 1-naphthol, cannot, however, satisfactorily fulfill all of the above requirements.